1. Field
This disclosure relates generally to microphones, and more specifically, to MEMS microphones.
2. Related Art
The use of microelectromechanical systems (MEMS) microphones has increased with the use of cellular telephones and the use of computers for voice transmission. MEMS microphones are much smaller so have been popular for those uses. With increased usage, tolerance for low performance has diminished. One difficulty with MEMS microphones has been high frequency response. If voice is the only usage, high frequency may not be required but the increased usage has increased the demand for a better response even at frequencies above those normally used for voice communication. The common requirement for high fidelity sound transmission is 20 to 20,000 hertz. One technique that has been used in MEMS microphones has been to provide a shielded package box around the MEMS devices with a small opening as the sound input. It has been difficult to achieve an opening and box that does not result in resonance frequencies within the operating range.
Accordingly, there is a need for a MEMS microphone that improves upon one or more of the issues discussed above.